The Ever-Surprising Chemistry of Boron: Enhanced Acidity of Phosphine⋅Boranes
作者:Marcela Hurtado、Manuel Yánez、Rebeca Herrero、Andrés Guerrero、Juan Z. Dávalos、José-Luis M. Abboud、Brahim Khater、Jean-Claude Guillemin
DOI:10.1002/chem.200802307
日期:2009.4.27
The acidity‐enhancing effect of BH3 in gas‐phase phosphine⋅boranes compared to the corresponding free phosphines is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. Thus, the enhancement of the acidity of protic acids by Lewis acids usually observed in solution is also observed in the gas phase. For example, the gas‐phase acidities (GA) of MePH2 and MePH2⋅BH3 differ
A chiral spirobifluorene-based bis(salen) zinc(<scp>ii</scp>) receptor towards highly enantioselective binding of chiral carboxylates
作者:Sk Asif Ikbal、Yoko Sakata、Shigehisa Akine
DOI:10.1039/d1dt00218j
日期:——
We have designed a newchiral receptor based on two salen zinc(II) complex units connected with a spirobifluorene framework. The chiral receptor is proven to enantioselectively bind chiral carboxylate guests and the differences between the binding constants of enantiomeric guests were up to more than one order of magnitude.
Design and evolution of an enzyme with a non-canonical organocatalytic mechanism
作者:Ashleigh J. Burke、Sarah L. Lovelock、Amina Frese、Rebecca Crawshaw、Mary Ortmayer、Mark Dunstan、Colin Levy、Anthony P. Green
DOI:10.1038/s41586-019-1262-8
日期:2019.6
that uses Nδ-methylhistidine as a non-canonical catalytic nucleophile. Histidine methylation is essential for catalyticfunction because it prevents the formation of unreactive acyl-enzyme intermediates, which has been a long-standing challenge when using canonical nucleophiles in enzyme design6–10. Enzyme performance was optimized using directed evolution protocols adapted to an expanded genetic code
In anodic oxidation of the phenylacetate ion, the formation yield of benzaldehyde increases by about 40% in the presence of a magnetic field (0.67 T), while 1,2-diphenylethane is insensitive to the field. The results are interpreted in terms of the magnetohydrodynamic mechanism.
that in the presence of clusters [Fe4S4(SR)4]2− (R=PhCH2 or But) and [M2Fe6S8(SEt)9]3− (M=Mo or W) the electroreduction of CO2 proceeds at the potential shifted by about 0.7 and 0.5 V, respectively, to the positive direction compared to the potential at which CO2 is reduced without any catalyst. When controlled potential electrolysis of a DMF solution containing [Fe4S4(SCH2Ph)4]2− was carried out under
一系列铁硫化合物的 DMF 溶液的电位-电流关系表明,在簇 [Fe4S4(SR)4]2- (R=PhCH2 或 But) 和 [M2Fe6S8(SEt)9]3- 存在下(M=Mo 或 W) 与 CO2 在没有任何催化剂的情况下还原的电位相比,CO2 的电还原在电位分别向正方向移动约 0.7 和 0.5 V 的情况下进行。当控制电位电解含有 [Fe4S4(SCH2Ph)4]2- 的 DMF 溶液在 -2.0 V vs. SCE 的 CO2 下进行时,作为 CO2 还原产生的产物形成苯乙酸盐和甲酸盐。在这些条件下,该星团的立方结构迅速坍塌。然而,当阴极电解液中加入过量的 PhCH2SH 时,簇结构在相对较长的电解过程中得以保留,